...am not sure, i don't have RB1 and RB2 to tell you if it works or not...

...i THINK (but PLEASE DON'T FOLLOW because this is what i JUST THINK might happen) that if you already put your songs onto RB2, you can delete the RB1 data and you would still have all the songs that you put from RB1 on RB2, but probably not with the scores and junk...

...once again, i do NOT own RB1 and RB2 so i am completely unsure about this

What ive read is that All the songs you have on Rock Band 1, You Pay and have the serial number in the back of the manual, to transfer them to Rock Band 2. This is for the 360 Im talking about. And This is confirmed by my friend that just did it recently, i asked him yea thats what he told me